HISTOLOGICAL GRADING AND BROMODEOXYURIDINE LABELING INDEX OF ASTROCYTOMAS - COMPARATIVE-STUDY IN A SERIES OF 60 CASES

The histological grade and the bromodeoxyuridine (BUdR) labeling index of 60 astrocytomas of "ordinary" cell types (fibrillary, protoplasmic, gemistocytic, and anaplastic astrocytomas and glioblastomas) were compared to determine whether the grading system reflects the proliferative potential of the tumors. The tumor grade was based on the presence or abscence of four criteria (nuclear abnormalities, mitosis, necrosis, and vasuclar endothelial proliferation): Grade 1, no criterion, Grade 2, one criterion, Grade 3, two criteria; and Grade 4, three of four criteria. The BUdR labeling index, or percentage of S-phase cells, was calculated in paraffin-embedded tumor sections after in situ labeling by intraoperative intravenous infusion of BUdR, 200 mg/sq m. Exponential regression analyses showed a positive correlation between the histological grade and labeling index (r = 0.88, p < 0.001) that was stronger than the correlations between log labeling index and age (r = 0.55, p < 0.001) and between grade and age (r = 0.55, p < 0.001). These results indicate that the histological grading system reflects the proliferative potential of "ordinary" astrocytomas.